(function(window,undefined) {
    let t = null

    $.fn.lazyLoad = function () {
        let _this = this  //jq对象
        function lazyLoad() {
            if (t) clearTimeout(t)
            t = setTimeout(() => {
                let windowH = window.innerHeight || document.documentElement.clientHeight
                let scrollH = document.body.scrollTop || document.documentElement.scrollTop
                let showH = windowH + scrollH

                let imgs =  _this

                for(let i = 0; i < imgs.length; i++){
                    if(imgs[i].offsetTop < showH) {
                        imgs[i].src = imgs[i].getAttribute('data-src')
                    }
                }
            },100)
        }
        lazyLoad() 
        window.onscroll = lazyLoad
    }
})(window)